Embodiments of the invention relate to a circuit arrangement with a thyristor circuit comprising at least one series circuit with at least two thyristors. Furthermore, embodiments of the invention relate to a method for testing such a thyristor circuit. Series circuits using several thyristors are frequently used to achieve a sufficiently high blocking voltage of a terminal with respect to a supply voltage and a redundancy. As a result of this, it is possible, for example, to avoid a destruction of the thyristors due to overvoltages. In doing so, it is desirable or required that the thyristors of the thyristor circuit be tested regarding their functionality.
Regarding this, prior art has provided suggestions. Considering the method for testing a thyristor known from publication DE 3640546 A1, an appropriate signal may be used in order to switch the thyristor into the conducting condition. A logic circuit verifies whether the thyristor is in its conducting condition, even though there is no appropriate control signal at its control input terminal. An appropriate error signal can be generated therefrom. Also, publication WO 93/11610 A1 has suggested monitoring the state of the circuit of a gate-turn-off thyristor by means of an appropriate monitoring logic circuit.
A method and a device for monitoring the functionality of electronic power components have been known from publication DE 10230527 A1. It suggests that a high-frequency electrical testing parameter be applied to the component to be tested. The voltage distribution due to the testing parameter is measured and, based thereon, the functionality of the tested component is determined.
Publication CN 101806853 A describes an online method for testing a thyristor. A resistor is connected in series to the thyristor, said resistor being connected to the anode. An RC member is connected between the anode and a thyristor driver. Additional terminals of the thyristor driver are connected to the control input of the thyristor as well as to the cathode. The current flowing through the series circuit consisting of the resistor and the thyristor, as well as the voltage at the resistor and the thyristor voltage between the anode and the cathode, are measured and transmitted to a control device. The control device energizes a switch that is provided parallel to the series resistor, so that the current and the voltage on the thyristor can be changed depending on whether the switch is open or closed. Depending on the energization of the switch and the measured values for current and voltage, it is possible to draw conclusions regarding the functionality of the thyristor.
Considering this prior art, the provision of a simple testing of a thyristor circuit may be regarded as being the object of embodiments of the invention.